Easy & Quick Rasam/saaru

Rasam is a very popular south Indian dish. A hot and spicy cup of Rasam is also a good soup. All special events seem to contain rasam. After having all the delicious heavy dishes in a celebration, most of us, would prefer to have nice hot rasam-rice (just before having curd rice :).
Whenever one of us is unwell, we prefer having rasam with rice. Feasting on a well made rasam-rice always gives a sense of satisfaction.